Improvement in safety-valves



s. cocKBunN.

Safety-Valves.

No. l46,873 l l PatemdJan.27,1a74.

UNITED STATES PATENT EEICEo GEORGE OOCKBURN, OF GLASGOW, NORTH BRITAIN.

IMPROVEMENT IN SAFETY-VALVES.l

Specification forming part of Letters Patent No. 146,873, dated January 27, 1874; application fill d December 9, 1873.

To all whom t may concern:

Be it known that I, GEORGE CocKEURN, of Glasgow, in the county of Lanark, North Britain, pattern-maker, have invented Im- Vunder pressure, and said disks having their edges, or those of the openings in which they tit, made bevelin g, to give free relief when the valve is lifted, and the disks exerting an additional or preponderating influence in raising the valve proper, over and above that which is due to the area of the latter. Y

In the accompanying drawing, Figure l represents a vertical section of a safety-valve having my invention applied to both its upper and under sides.'v Figs. 2 and 3 are vertical sections, showing the invention applied to the under side of the valve only, under different forms of general construction.

Similar letters of reference indicate corresponding parts.

Referring, in thefirst instance or more particularly, to Fig. l of the dra-wing, A is the valve proper, and B the valve casing or seat, inelosed by a chamber, C. D is a plate or disk, ofA larger diameter or area than the valve A, secured to the lower part of the valve A by a nut, b, made to lit aserew-thread, c, formed at the lower part of the valve A. Between the outer marginal portion of the disk D and a lower chambered portion, E, of the valve-casing, an annular space, d, is formed, through which steam, supposing the invention to be applied to a steam-boiler, passes into the chamber E. The downward weight or load upon the valve is represented by a helical spring; but it may be by a weight or weights, or by a lever and weight.

Then the pressure of steam upon the under side of the valve exceeds the resistance pre sented by the load, and the valve begins to rise from its seat, the steam escapes 'from the chamber Fi, and by so doing the pressure within said chamber is reduced-that is to say, the pressure on the upper side of the plate or disk D becomes less than the pressure on the under side thereof. This sudden reduction of pressL ure above the disk D momentarily gives the steam acting on the under side of the disk a preponderating iniiuence to raise the valve A farther from its seat, thus imparting to the valve a greater relieving eect than would be due to it without the disk or plate D.

Stops c are arranged on the upper side of the disk D, to limit the extent of its lift. The periphery of the disk D is curved or beveled, as at f, to a greater or less extent, as indicated by dotted lines in Fig. 2, so that, as the valve is lifted to a greater or less extent, the diference of pressure above and below the disk or plate D is variable.

Instead, however, of forming the periphery ofthe disk or plate curved or beveled, as shown at fin Fig. l, the curved or beveled surface may be formed on the angular opening surrounding the disk, which beveled construction of the opening cl in a reverse direction to that shown for the periphery of the disk D is equivalent to beveling the edges of the disk.

The valve A in Fig. l is also shown with a disk, D', on its upper side, tting within an upper chamber, E', and curved, .eut away, or beveled at its edge, as in the case of the lower disk; or the annular opening of the chamber' in which said upper disk fits may be curved, cut away, or beveled instead, as and for the purpose hereinbefore referred to with reference to the lower disk.

'Vhen the pressure of steam on the under side of the valve A exceeds the load, and the valve rises from its seat, the steam passes into the chamber E', and from thence outward through the annular space surrounding the disk, and, accordingly as the outward passage of the steam is retarded by a greater or less curvature or bevel-on the edge of either disk 0r its surrounding opening, as the case may be, or, in other words, according to the extent of the opening, so will the steam, after passing over the valve-seat, aet upon the bot-tom of the chamber E', and so enable the steam to exert au additional or preponderatiug iniiuence in lifting the valve over or above that which is due to the area of the valve proper. The upper disk 1) is, accordingly, but a supplement of the lower disk l), and acts in the saine inanner for a like purpose, but still further increases the efficiency of the Valve as regards its relieving effect. Either the upper or lower disk, however, may only be used, it'ilesired, instead of being used eonjointly, as in Fig. l. Thus, in Fig. 2 of the drawing, which represent-s the invention as applied to a lock-up safetyvalve, the lower disk D only is used. Such also is the case in the niodifieation shown in. Fig. il.

I claim- 'lhe combination, with the valve ropei: A and its easing or seat B, of one or more pistonlike disks, ll) 1)', of greater area Vthan said Valve, and one or more receiving-ehainbers, E Ef, for the steam, gas, or vapor under pressure, said disks, in connection With the chambers E E', operating t0 assist in raising the valves, and being beveled on their edges to give a quick relief, substantially as shown and described.

In testimony whereof I have signed my name to this specification in. the presence et" two subscribing witnesses.

GEORGE (JOC l( RU RN.

v\\'itnesses:

EDWARD FIsHER Bauman, JOHN CAMPBELL MAeANDIn. 

